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Context. At present, there are strong indications that white dwarf (WD) stars with masses well below the Chandrasekhar limit ( M Ch ≈ 1.4 M ⊙ ) contribute a significant fraction of SN Ia progenitors. The relative fraction of stable iron-group elements synthesized in the explosion has been suggested as a possible discriminant between M Ch and sub- M Ch events. In particular, it is thought that the higher-density ejecta of M Ch WDs, which favours the synthesis of stable isotopes of nickel, results in prominent [Ni II ] lines in late-time spectra (≳150 d past explosion). Aims. We study the explosive nucleosynthesis of stable nickel in SNe Ia resulting from M Ch and sub- M Ch progenitors. We explore the potential for lines of [Ni II ] in the optical an near-infrared (at 7378 Å and 1.94 μm) in late-time spectra to serve as a diagnostic of the exploding WD mass. Methods. We reviewed stable Ni yields across a large variety of published SN Ia models. Using 1D M Ch delayed-detonation and sub- M Ch detonation models, we studied the synthesis of stable Ni isotopes (in particular, 58 Ni) and investigated the formation of [Ni II ] lines usingmore »
We present optical photometry and spectroscopy of the Type II supernova ASASSN-14jb, together with Very Large Telescope (VLT) Multi Unit Spectroscopic Explorer (MUSE) integral field observations of its host galaxy and a nebular-phase spectrum. This supernova, in the nearby galaxy ESO 467-G051 ( z = 0.006), was discovered and followed-up by the all-sky automated survey for supernovae (ASAS-SN). We obtained well-sampled las cumbres network (LCOGTN) B V g r i and Swift w 2 m 1 w 1 u b v optical, near-UV/optical light curves, and several optical spectra in the early photospheric phases. The transient ASASSN-14jb exploded ∼2 kpc above the star-forming disk of ESO 467-G051, an edge-on disk galaxy. The large projected distance from the disk of the supernova position and the non-detection of any H II region in a 1.4 kpc radius in projection are in conflict with the standard environment of core-collapse supernova progenitors and suggests the possible scenario that the progenitor received a kick in a binary interaction. We present analysis of the optical light curves and spectra, from which we derived a distance of 25 ± 2 Mpc using state-of-the-art empirical methods for Type II SNe, physical properties of the SN explosion ( 56 Ni mass, explosionmore »
We analyse new multifilter Hubble Space Telescope (HST) photometry of the normal Type Ia supernova (SN Ia) 2011fe out to ≈2400 d after maximum light, the latest observations to date of a SN Ia. We model the pseudo-bolometric light curve with a simple radioactive decay model and find energy input from both 57Co and 55Fe are needed to power the late-time luminosity. This is the first detection of 55Fe in a SN Ia. We consider potential sources of contamination such as a surviving companion star or delaying the deposition time-scale for 56Co positrons but these scenarios are ultimately disfavored. The relative isotopic abundances place direct constraints on the burning conditions experienced by the white dwarf (WD). Additionally, we place a conservative upper limit of <10−3 M⊙ on the synthesized mass of 44Ti. Only two classes of explosion models are currently consistent with all observations of SN 2011fe: (1) the delayed detonation of a low-ρc, near-MCh (1.2–1.3 M⊙) WD, or (2) a sub-MCh (1.0–1.1 M⊙) WD experiencing a thin-shell double detonation.
Aims . We present a comprehensive dataset of optical and near-infrared photometry and spectroscopy of type Ia supernova (SN) 2016hnk, combined with integral field spectroscopy (IFS) of its host galaxy, MCG -01-06-070, and nearby environment. Our goal with this complete dataset is to understand the nature of this peculiar object. Methods . Properties of the SN local environment are characterized by means of single stellar population synthesis applied to IFS observations taken two years after the SN exploded. We performed detailed analyses of SN photometric data by studying its peculiar light and color curves. SN 2016hnk spectra were compared to other 1991bg-like SNe Ia, 2002es-like SNe Ia, and Ca-rich transients. In addition, we used abundance stratification modeling to identify the various spectral features in the early phase spectral sequence and also compared the dataset to a modified non-LTE model previously produced for the sublumnious SN 1999by. Results . SN 2016hnk is consistent with being a subluminous ( M B = −16.7 mag, s B V =0.43 ± 0.03), highly reddened object. The IFS of its host galaxy reveals both a significant amount of dust at the SN location, residual star formation, and a high proportion of old stellar populations in themore »
A Physical Basis for the H-band Blue-edge Velocity and Light-curve Shape Correlation in Context of Type Ia Supernova Explosion Physicshttps://doi.org/https://ui.adsabs.harvard.edu/link_gateway/2019ApJ...878...86A/doi:10.3847/1538-4357/ab204bOur recent work demonstrates a correlation between the high-velocity blue edge, vedge, of the ironpeak Fe/Co/Ni H-band emission feature and the optical light curve shape of normal, transitional and sub-luminous type Ia Supernovae (SNe Ia). We explain this correlation in terms of SN Ia physics. vedge corresponds to the sharp transition between the complete and incomplete silicon burning regions in the ejecta. It measures the point in velocity space where the outer 56Ni mass fraction, XNi, falls to the order of 0.03-0.10. For a given 56Ni mass, M(56Ni), vedge is sensitive to the speci c kinetic energy Ekin(M(56Ni)=MWD) of the corresponding region. Combining vedge with light curve parameters (i.e., sBV , m15;s in B and V ) allows us to distinguish between explosion scenarios. The correlation between vedge and light-curve shape is consistent with explosion models near the Chandrasekhar limit. However, the available sub-MCh WD explosion model based on SN 1999by exhibits velocities which are too large to explain the observations. Finally, the sub-luminous SN 2015bo exhibits signatures of a dynamical merger of two WDs demonstrating diversity among explosion scenarios at the faint end of the SNe Ia population.